[Amps] Commander HF-1250 problem

[doug ferguson]

Hi,
My HF-1250 just went out.  It was working fine and then the lights and fan
started flickering for about 5 seconds and then the whole thing went dark.
No smells or sounds and no apparent burn marks that I can see.  The power
supply components involve taking the entire amp apart to check so was hoping
someone can give me some other ideas before I have to do that.
The fuses are both good; wall power, the front power switch and interlock switch are good.
Not sure if these amps have thermal fuses in the transformer? The schematic doesn't show
one although they usually don't.
Would a shorted 3cx800a7 cause this?  Like I said, it went slowly and quietly - no bangs, 
pops or smells or broken components that I can see. It just won't turn on.  
Any help on where to start would be greatly appreciated.
73,
Doug - N7NM